docs: def getReturnPage(siteHistory,prior=False):
      '''
      This helper function is called in various places to get the return page from current
      session data.  The session data (in the 'SITE_HISTORY' key) is a required argument.
      '''
  
      expiry = parse_datetime(
          siteHistory.get('expiry',''),
      )
      if prior:
          returnPage = siteHistory.get('priorPage',None)
          returnPageName = siteHistory.get('priorPageName',None)
      else:
          returnPage = siteHistory.get('returnPage',None)
          returnPageName = siteHistory.get('returnPageName',None)
  
      if expiry and expiry >= timezone.now() and returnPage[0]:
          return {
              'url': reverse(returnPage[0],kwargs=returnPage[1]),
              'title': returnPageName,
          }
      else:
          return {'url': None, 'title': None}